Thread Loss Issue

We are seeing an error in our SQL Server logs I'm not very familiar with, and
was hoping someone on here could shed some light on the subject...

I installed the SS DBA Dashboard on one of our boxes. This box is a 64 bit
Windows Server 2003, SP2 running SQL Server 2005 64 bit, Service PAck 2 with
Cumulative Update 3 applied. The entire box has 16GB or RAM and 16
processors. We have 12GB of RAM devoted exclusively to SQL Server, which is
allocated on start up.

Here is the error we're getting:

08/26/2008 04:55:04,spid147,Unknown,AppDomain 62
(SS_DBA_Dashboard.dbo[runtime].61) created.
08/26/2008 04:54:59,spid1s,Unknown,AppDomain 61
(SS_DBA_Dashboard.dbo[runtime].60) unloaded.
08/26/2008 04:54:59,spid1s,Unknown,AppDomain 61
(SS_DBA_Dashboard.dbo[runtime].60) is marked for unload due to memory
pressure.
08/26/2008 04:49:06,spid91,Unknown,AppDomain 61
(SS_DBA_Dashboard.dbo[runtime].60) created.
08/26/2008 04:48:17,spid1s,Unknown,AppDomain 60
(SS_DBA_Dashboard.dbo[runtime].59) unloaded.
08/26/2008 04:48:17,spid1s,Unknown,AppDomain 60
(SS_DBA_Dashboard.dbo[runtime].59) is marked for unload due to memory
pressure.

These AppDomains appear to be under some kind of pressure, then get
unloaded, then a new one gets created. There is a stored procedure that runs
every minute...

The DBA Dashboard consists of one .dll, two stored procedures and a very
small database. The stored procedure gets run every minute and gather stats
on database activity. Here's a link to the application:

http://www.sqlserverexamples.com/v2/...6/Default.aspx

I've been reading and keep coming across this issue, but have only seen it
in relation to shops running on 32 bit platofrms.

I have no idea what the scoop is here, but am assuming it's got something to
do with .Net somehow

Any insight would be appreciated!